Both Information and electronics technologies have known a rapid, spectacular development. Further, over the past decade there has been a simultaneous growth in computer, mobile communication, and network leading to an increasing use of related products. Recently, there is a trend of developing compact, multifunctional, and inexpensive communication products. A number of products such as cellular phones and Personal Digital Assistants (PDAs) closely related to our daily life are very popular among consumers. The increasing popularity of such portable communication devices not only shortens distance between people but also reduces time required for achieving the communication. Moreover, features and quality required by consumers are diversified and high as a variety of communication products have been commercially available. As such, a leading indicator regarding the manufacturing technology of communication product can be decided by determining whether it can provide more convenient, more effective, and multi-functional services to users.
Quite often, more and more newer models of cellular phone have the capability of sending, receiving e-mails and accessing a network (e.g., the Internet) in real time. As such, a user can retrieve latest information by using the cellular phone at any time and place without being adversely affected by geography. However, the well-known cellular phone does not provide any safety action. As such, a third party may illegally intercept credentials being sent or received by a cellular phone or an electronic list being signed online. This can cause significant loss to the user. Therefore, it is desirable for communication product manufacturers to provide means for enabling a cellular phone user to sign an electronic list online at any time and place and safely sending the electronic list over the Internet without being affected by geography, buildings, and locations.